There is a need for headlamp cleaning systems on vehicles because headlamps collect light distorting residue. Dirty headlamps reduce visibility and cause a glare to on-coming traffic. Some systems activate a headlamp cleaning system whenever the windshield wiping assembly is activated. However, headlamps of a vehicle typically accumulate dirt faster than windshields. A problem arises in this type of system because neither the headlight cleaning system nor the windshield wiping system can be activated independently of the other. There are times when only the headlamp cleaning system or the windshield wiping system needs to be activated.
One type of assembly for independently activating a headlight cleaning system includes the use of photodiodes positioned on the exterior of a headlamp. The photodiodes will extend partially over the headlamp lens to receive light coming from behind the lens. When dirt or residue accumulates on the lens, less light will pass from the lens and thus less light will be sensed by the photodiodes. When a predetermined threshold is exceeded, the washing means is activated. A problem with this type of assembly is that the light sensor is mounted on the exterior of the headlamp which is subject to dirt and damage. The U.S. Pat. No. 3,609,450 granted Sept. 28, 1971 in the name of Atlee F. Hart discloses such a system where photodiodes sense the light coming through the lens from the light source to actuate a cleaning means when the sensed light falls below a predetermined magnitude.